Delay actuator



S. A. AMSTER March 4, 1969 DELAY ACTUATOR Sheet Filed Oct. 12, 1967 FIG. 5

oe/ax 4 R M, m Z WMMX b/ 47 a! w United States Patent O 3,430,568 DELAY ACTUATOR Stanley A. Amster, Pittsburgh, Pa., assignor to Federal Laboratories, Inc., Saltsbnrg, Pa., a corporation of Pennsylvania Filed Oct. 12, 1967, Ser. No. 674,865

U.S. Cl. 10282 Int. Cl. F42c 9/06, 9/02 3 Claims ABSTRACT OF THE DISCLOSURE Background of the invention This invention relates to a delayed action means for firing a grenade or similar explosively actuated device. It has particular reference to the means for establishing a positive time interval between the throwing of the grenade and the detonation of the charge.

All grenades and many other types of projectiles require a time delay between the start of a trajectory and the explosive action. Some prior art devices have employed clock mechanisms but most have used a pyrotechnic fuse to delay the action. Fuses are not reliable, sometimes carrying a burning stream too fast and sometimes not functioning at all. A clock is too easily damaged to function in a projectile where shock forces are high.

The present invention uses sturdy moving components which cannot be damaged by any shock normally associated with its use. It is positive in action and always includes a time delay which is suflicient to last until the explosive device is within range of a target. All elements are fully enclosed and are protected from atmospheric moisture.

For a better understanding of the present invention, together with other details and features thereof, reference is made to the following description taken in connection with the accompanying drawings.

Brief description of the drawings FIGURE 1 is a cross sectional view of a grenade actuating mechanism showing two pistons and a discharge actuator.

FIGURE 2 is a cross sectional view of the mechanism shown in FIGURE 1 and is taken along line 2-2 of that figure.

FIGURE 3 is a cross sectional view similar to FIG- URE 1 but showing the latching lever removed from the mechanism and the first piston moving toward its final position.

FIGURE 4 is a cross sectional view similar to that shown in FIGURES 1 and 3 with both pistons at the end of their travel and with the explosive charge detonated.

FIGURE 5 is a top view of the device as shown in FIGURE 1 and is taken along line 5-5 of that figure.

Description of the preferred embodiment The delay actuator is shown in detail in FIGURES 1 and 3 and includes a housing which encloses two hollow cylinders 11 and 12. Cylinder 11 contains a first pis ton 13 having a rod 14 extending therefrom. The rod Patented Mar. 4, 1969 14 normally extends through a hole 14A and beyond the top surface of the housing 10. An annular groove 15 in rod 14 also extends above the upper surface of the housing and is for latching into a starting position by means of a latching lever 15A having an end fork 16. A coil spring 17 is disposed around the rod 14 between the piston 13 and the top of the cylinder 11. The spring 17 is compressed in the loaded position of the actuating device. A small hole 18 is bored through the piston 13 in order to form a path for escaping air when the piston 13 is released as hereinafter more fully set forth. One or more O-rings 19 may be positioned in the cylindrical surface of piston 13 in order to provide an air tight joint between the piston and the inside surface of cylinder 11. The piston 13 together with the spring 17 may be inserted into the cylinder 11 and then secured in this position by means of threaded plug 20 or any other fastening means to retain the plug in the position shown in FIGURES 1 and 3.

The latching lever 15A is provided with an arm 45 which may be held in position by a .pin 21. The latching means 15A is provided with a helical spring 22 which is compressed as long as the latching lever is in its normal position held by pin 21. The pin 21 may be coupled to a hand ring 23 for easy withdrawal of the pin when the device is conditioned for action.

A second piston 24 is positioned in the second hollow cylinder 12 and is urged downwardly by a helical spring 25. The second piston 24 is formed with a central point 26 for exploding the material in a primer exploding cap 27 installed in the lower cylinder head 28. The second piston 24 is formed with a chamfered lower edge 29. A spherical ball 30 is positioned between two springs 31 and 32 (see FIGURE 2) enclosed in a hole drilled through the wall 46 between the cylinders 11, 12. After the ball 30 and springs 31, 32 are installed, screw caps 33 and 34 are installed as shown to retain the .ball in its central position. The springs may be replaced by solid extensions of the caps 33, 34 if desired. In the loaded position, the ball 30 rests against one side of piston 13 and makes contact with the chamfered portion 29 of the second pitson 24, holding it in the position shown in FIGURES 1 and 3.

The second cylinder plug 28 may be secured to the cylinder 12 by conventional screw threads or by any other convenient fastening means. A central hole 36 is formed in cylinder plug 28 so that the hot gases from the primer cap 27 may move through the hole to ignite a booster charge 37 and a detonator 38. The booster charge 37 and the detonator 38 may have shapes different than those shown in FIGURES 1 and 3 and they may be secured to the cylinder head 28 by other means. They are, however, set off by the primer 27 through the hole 36. It is believed that the separation of the primer 27 and booster 37 is important because the device as illustrated in the figures may be used many times to explode projectiles. Since the device is quite rugged and since there are no explosive charges in the main portion of the device, a new primer 27 can be added and the other explosive components 37 and 38 may be attached by crimping to the lower end of the cylinder head 28. A threaded portion 40 is provided for securing the device to the grenade or other device to be detonated.

When an operator desires to explode the device, the ring 23 is employed to pull pin 21 from the device. The grenade may be held in the hand with the fingers holding the latching lever 45 in place after the pin has been removed. When the grenade is thrown, spring 22 forces the latching means 45 from the grenade pulling the forked portion out of the rod 14. The rod 14 together with the first piston 13 is urged downwardly by the helical spring 17. The air trapped in the lower part of cylinder 11 slowly escapes through hole 18 as the piston 13 is forced into the cylinder 11 by the spring 17. As shown in FIGURE 3, with the pin 21, the lever 45 and the helical spring 22 detached from the device the first piston 13 moves to a position about half-way between its latched position and the final position as shown in FIGURE 4. It is obvious from FIGURE 3 that the retaining ball 30 still holds the second piston 24 in its start position.

However, as the piston 13 moves further it reaches the bottom of the hollow cylinder 11 as shown in FIGURE 4. Just before reaching its final position, the upper edge of piston 13 releases ball 30 which is cammed into the hollow cylinder 11 by the chamfer surface 29 on the second piston 24. The second piston 24 is thereby released and moves rapidly to its lower position urged by helical spring 25. The point 26 punctures the primer 27 exploding it and also exploding the booster charge 37 and the detonator 38.

The figures show both hollow cylinders formed from a single block since this is the most convenient method of fabrication. The figures also show two supporting cars 41 for holding the reatining pin 21 and its ring 23. It is obvious that two separate hollow cylinders may be used instead of the single block formation and that any other type of pivoting means can be used instead of the ears 41. If the detonator .38 and the explosive it triggers do not damage the plug 28, the device may be used again. Even if the plug is somewhat damaged, a new plug 28 can be screwed into place and the device used many times.

Having thus fully described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A delay actuator for firing an explosive cap, comprising first and second hollow cylinders disposed in parallel alignment:

a first piston slidably carried within the first cylinder and including a hole cut in the piston for the transfer of air from one side of the piston to the other, a

rod carried by the first piston and extending through the first cylinder in the loaded position, and a first resilient means for urging the first piston toward a discharge position;

a second piston slidably carried within the second cylinder, a firing point on said second piston, a chamfered edge on the lower portion of the piston for engagement with a piston retaining means, and a second resilient means for urging the second piston toward a firing position;

mechanical retaining means disposed between the first and second pistons, normally engaging the chamfer surface of the second piston and the cylindrical surface of the first piston in the loaded position, and means to release the first piston whereby the retaining means is disengaged from the second piston to permit the resilient means to drive the second piston to its firing position.

2. A delay actuator as claimed in claim 1 wherein said rod is formed with an annular groove at its outer end for engagement with a removable latch.

3. A delay actuator as claimed in claim 2 wherein said removable latch includes a removable pivot pin which normally holds the latch in place, and a resilient means which urges the latch out of engagement with the rod when the pivot pin is removed.

References Cited UNITED STATES PATENTS 896,135 8/1908 Meigs et al. 10282 2,149,469 3/1939 Schenk 102-83 3,048,111 8/1962 Baker et al. 102 3,296,969 1/ 1967 Mueller et al. 10282 FOREIGN PATENTS 742,598 3/ 1933 France.

BENJAMIN A. BORCHELT, Primary Examiner.

GERALD H. GLANZMAN, Assistant Examiner.

U.S. Cl. X.R. 10265 .4 

